FOX47 NEWS - Columbus Macklin "Mack" Jensen Memorial

Columbus High School is planning a memorial service for the student who died playing the choking game.

Macklin "Mack" Jensen, 17, died Friday.

"He was an amazing young man," said Connie Valenza, Columbus High School principal. "He was involved in our athletic program. He was a football player, outstanding wrestler."

Mack also swam competitively and played saxophone in the marching band.

"Many different groups of kids are grieving and missing him," Valenzasaid. "As our activities go on over the course of the year, his absenceis going to be noted in many places."

The teenager died after playing what is known as the choking game.

"Asphyxiation is what it is," said Anthony Callisto, M.D., Sun Prairie Emergency Medical Center director. "They play this game where they choke themselves. Whether it's using a belt or rope, or have other people come behind them, and physically put their arm around them -- that's the game."

Kids have come up with other names for it, too -- "blackout," "spacemonkey," and "gasp." Doctors says what makes the act so deadly is thespeed at which it can kill.

"You have about a minute to restore blood flow to the brain before brain damage starts," Dr. Callisto said. "So, it's a slippery curve. You don't have much time. It's very dangerous."

There are signs to look for to tell of your child is playing the choking game -- they include bruises around the neck, broken blood vessels in the eyes, and finding belts and ropes in places they should not be.